The present invention relates to an apparatus and a method for controlling an internal combustion engine in which a spark ignition combustion mode and a compression ignition combustion mode are switched in accordance with operation conditions and more particularly to such control apparatus and method suitable for control of switching the combustion mode from the spark ignition combustion mode to the compression ignition combustion mode.
In a gasoline engine, there is known an internal combustion engine in which the spark ignition combustion mode in which an air-fuel mixture is spark-ignited by means of an igniter and the compression ignition combustion mode in which the air-fuel mixture is self-ignited by piston compression are switched in accordance with operation conditions.
In the internal combustion engine of the compression ignition combustion system adopting the combustion system in which the air-fuel mixture is compressed to be self-ignited, it is necessary to control the self-ignition combustion in the highly efficient and wide operation area suitably and to control switching of the self-ignition combustion and the spark ignition combustion suitably.
As technique related to the above technique, there is the technique in which stratified charge combustion mode is performed upon switching of the combustion mode of the spark ignition and the compression ignition to thereby suppress variation in torque (for example, JP-A-2001-152919).